The present invention relates to an improved apparatus for generating a decelerating command at the terminating floor of an elevator.
The speed of an elevator cage is controlled in accordance with a speed command value. A terminating deceleration command value is produced for protecting the speed command value at the terminating floor. This is shown in FIGS. 1 to 3.
In FIGS. 1 to 3, numeral 1 designates a speed instructing unit which generates a normal speed command value V.sub.p, numeral 2 a selecting circuit which selects either a smaller value than the speed command value V.sub.p or a terminating deceleration command value V.sub.s, which will be described later, numeral 3 an adder which adds the output of the selecting circuit 2 and a speed signal, which will be described later, and which outputs a deviation signal between the output of the selecting circuit 2 and the speed signal, numeral 4 a speed controller which outputs a speed control signal in response to the deviation signal, numeral 5 a thyristor converter which comprises thyristors and which has its output voltage controlled in accordance with the speed control signal, numeral 6 an armature of a winding D.C. motor which is connected to the thyristor converter 5, numeral 7 a tachometer generator which is coupled directly to the armature 6 and which produces a speed signal which is inputed to the adder 3, numeral 8 a sheave for a winch which is driven by the armature 6, numeral 9 a deflector wheel, numeral 10 a main cable which is engaged with the sheave 8 and the deflector wheel 9, numeral 11 a cage which is coupled to one end of the main cable 10, numeral 12 a balance weight which is similarly coupled to the other end of the main cable 10, numeral 13 a cam which is fixedly secured to the case 11, numeral 14 the top floor, numeral 15 the bottom floor, numerals 16 to 20 terminating detectors which are respectively provided in an elevational passage so as to be sequentially disposed toward the top terminating floor 14 and which successively operate when each is engaged with the cam 13, numerals 16a to 20a their normally closed contacts (in FIG. 2), numerals 21 to 25 terminating detectors which are similarly respectively provided in the elevational passage so as to be sequentially disposed toward the bottom terminating floor 15, numerals 21 a to 15a their normally closed contacts (in FIG. 2), and numeral 26 a terminating deceleration instructing unit which produces the terminating deceleration command value V.sub.s in accordance with the outputs of the detectors 16 to 26. In FIG. 2, numeral 27 designates an ascending operation relay contact which closes when the cage 11 ascends, numeral 28 a descending operation relay contact which closes when the cage 11 similarly descends, numeral 29 an operational amplifier, characters R.sub.1 to R.sub.5, R.sub.11 to R.sub.15 and R.sub.s resistors, character C a capacitor, and character -V.sub.ee a D.C. negative power voltage.
As shown in FIG. 3, since the voltages V.sub.p and V.sub.s are normally set to the relationship of V.sub.p &lt;V.sub.s, the selecting circuit 2 selects the speed command value V.sub.p, the speed controller 4 operates in accordance with this speed command value V.sub.p, thereby operating the thyristor coverter 5, which in turn applies a voltage to the armature 6 of the motor. Thus, the armature 6 rotates, thereby running the cage 11 through the sleeve 8 and the main cable 10. The speed of the case 11 is detected by the tachometer generator 7, the speed signal of the tachometer generator 7 is compared by the adder 3 with the speed command value V.sub.p, and the cage 11 is accurately controlled in accordance with the speed command value V.sub.p.
When the cage 11 is, on the other hand, ascending along an intermediate floor, the ascending operation relay contact 27 remains closed, and the terminating detectors 16 to 20 are not activated. Accordingly, their contacts 16a to 20a are all closed. Therefore, the terminating deceleration command value V.sub.s becomes, as shown in FIG. 3, V.sub.s =V.sub.1. When the cage 11 continues to ascend and reaches a point S.sub.1, the detector 16 engages with the cam 13, allowing the contact 16a to open. Thus, the input resistor R.sub.1 of the amplifier 29 is disconnected from the power voltage -V.sub.ee, and the terminating deceleration command value V.sub.s decrease, as shown in FIG. 3, at a time constant which is determined by the resistor R.sub.s and the capacitor C and eventually becomes a voltage V.sub.2. When the cage 22 further ascends and reaches a point S.sub.2, the detector 17 operates, allowing the contact 17a to open. Thus, the terminating deceleration command value V.sub.s similarly decreases at the time constant and eventually becomes a voltage V.sub.3. Similarly, the detectors 18, 19 operate, and the terminating deceleration command value V.sub.s decreases. When the cage 11 thus finally reaches a point at a distance S.sub.5 before the floor 14, the detector 20 operates, allowing the contact 20a to open, and the terminating deceleration command value V.sub.s decreases toward zero.
When the speed command value V.sub.p does not decreases and the values V.sub.p and V.sub.s becomes V.sub.p &lt;V.sub.s even if a malfunction occurs in the speed instructing unit and the cage 11 approaches the vicinity of the top floor 14, the selecting circuit 2 selects the terminating deceleration command value V.sub.s. Thus, the cage 11 decelerates and stop at the top floor 14 in accordance with the terminating deceleration command value V.sub.s.
In case of the descending operation, the operation is performed similarly to the case of the ascending operation except that the descending operation relay contact 28 closes and the terminating detectors 21 to 25 operate.
In this case, the deceleration of the terminating deceleration command value V.sub.s should be set as low as possible so as to protect the thyristor and the motor against an excessively large current at the decelerating time. For that purpose, a number of terminating detectors 16 to 25 should be provided. Since the detectors 16 to 25 are, on the other hand, restricted in their disposition, the number of the detectors should be limited. Accordingly, the deceleration of the terminating deceleration command value V.sub.s cannot be reduced to a sufficient value, and the thyristor and the motor employed become rigid and expensive.